Prenatal antimicrobial use and early-childhood body mass index.

BACKGROUND/OBJECTIVES: Growing evidence suggests that antibiotic use is associated with childhood body mass index (BMI), potentially via mechanisms mediated by gut microbiome alterations. Less is known on the potential role of prenatal antimicrobial use in offspring obesity risk. We examined whether prenatal antibiotic or antifungal use was associated with BMI at the age of 2 years in 527 birth cohort participants. METHODS/SUBJECTS: Antimicrobial use was obtained from the prenatal medical record. Height and weight were measured at the age of 2 years. Overweight/obesity was defined as a BMI ⩾85th percentile. RESULTS: A total of 303 (57.5%) women used antibiotics and 101 (19.2%) used antifungals during pregnancy. Prenatal antifungal use was not associated with child BMI at the age of 2 years. In the fully adjusted model, prenatal antibiotic use was associated with a 0.20±0.10 (P=0.046) higher mean BMI Z-score at the age of 2 years. Associations between prenatal antibiotic use and childhood BMI varied by trimester of exposure, with first or second-trimester exposure more strongly associated with larger BMI at the age of 2 years for both BMI Z-score (interaction P=0.032) and overweight/obesity (interaction P=0.098) after covariate adjustment. CONCLUSIONS: Prenatal antibiotic, but not antifungal, use is associated with larger BMI at the age of 2 years; associations were stronger for antibiotic exposures in earlier trimesters. Future studies examining whether these associations are due to alterations in the maternal and/or infant microbiome are necessary. Children who are overweight at the age of 2 years are at higher risk for being overweight as they age; prenatal antibiotic use is a potentially modifiable exposure that could reduce childhood obesity.

Dog introduction alters the home dust microbiota.

Research has largely reported that dog exposure is associated with reduced allergic disease risk. Responsible mechanism(s) are not understood. The goal was to investigate whether introducing a dog into the home changes the home dust microbiota. Families without dogs or cats planning to adopt a dog and those who were not were recruited. Dust samples were collected from the homes at recruitment and 12 months later. Microbiota composition and taxa (V4 region of the 16S rRNA gene) were compared between homes that did and did not adopt a dog. A total of 91 dust samples from 54 families (27 each, dog and no dog; 17 dog and 20 no dog homes with paired samples) were analyzed. A significant dog effect was seen across time in both unweighted UniFrac and Canberra metrics (both P = .008), indicating dog introduction may result in rapid establishment of rarer and phylogenetically related taxa. A significant dog-time interaction was seen in both weighted UniFrac (P < .001) and Bray-Curtis (P = .002) metrics, suggesting that while there may not initially be large relative abundance shifts following dog introduction, differences can be seen within a year. Therefore, dog introduction into the home has both immediate effects and effects that emerge over time.

Novel microbiome-based therapeutics for chronic rhinosinusitis.

The human microbiome, i.e. the collection of microbes that live on, in and interact with the human body, is extraordinarily diverse; microbiota have been detected in every tissue of the human body interrogated to date. Resident microbiota interact extensively with immune cells and epithelia at mucosal surfaces including the airways, and chronic inflammatory and allergic respiratory disorders are associated with dysbiosis of the airway microbiome. Chronic rhinosinusitis (CRS) is a heterogeneous disease with a large socioeconomic impact, and recent studies have shown that sinus inflammation is associated with decreased sinus bacterial diversity and the concomitant enrichment of specific sinus pathogens. Here, we discuss the potential role for probiotic supplementation for CRS in light of this increasing understanding of the airway microbiome and microbial interactions with the host. We focus on the ecological significance of microbiome-based probiotic supplementation and potential interactions with the gastrointestinal tract and consider microbial administration methods for treatment of CRS.

Rearrangement of a large novel Pseudomonas aeruginosa gene island in strains isolated from a patient developing ventilator-associated pneumonia.

Bacterial gene islands add to the genetic repertoire of opportunistic pathogens. Here, we perform comparative analyses of three Pseudomonas aeruginosa strains isolated sequentially over a 3-week period from a patient with ventilator-associated pneumonia (VAP) who received clindamycin and piperacillin-tazobactam as part of their treatment regime. While all three strains appeared to be clonal by standard pulsed-field gel electrophoresis, whole-genome sequencing revealed subtle alterations in the chromosomal organization of the last two strains; specifically, an inversion event within a novel 124-kb gene island (PAGI 12) composed of 137 open reading frames [ORFs]. Predicted ORFs in the island included metabolism and virulence genes. Overexpression of a gene island-borne putative ß-lactamase gene was observed following piperacillin-tazobactam exposure and only in those strains that had undergone the inversion event, indicating altered gene regulation following genomic remodeling. Examination of a separate cohort of 76 patients with VAP for integration at this tRNA(lys) recombination site demonstrated that patients exhibiting evidence of integration at this site had significantly higher 28-day mortality. These findings provide evidence that P. aeruginosa can integrate, rapidly remodel, and express exogenous genes, which likely contributes to its fitness in a clinical setting.

PcrV antibody-antibiotic combination improves survival in Pseudomonas aeruginosa-infected mice.

The type III secretion system (TTSS) of Pseudomonas aeruginosa, associated with acute infection, facilitates the direct injection of cytotoxins into the host cell cytoplasm. Mab166, a murine monoclonal antibody against PcrV, a protein located at the tip of the injectisome, has demonstrated efficacy against P. aeruginosa infection, resulting in reduced lung injury and increased survival in murine models of infection. We hypothesised that the administration of Mab166 in combination with an antibiotic would further improve the survival of P. aeruginosa-infected mice. A murine model of P. aeruginosa acute infection, three clinically relevant antibiotics (ciprofloxacin, tobramycin and ceftazidime) and the Mab166 antibody were used for this study. Consistently, compared to other treatment groups (antibiotic or antibody administered in isolation), the combination of Mab166 and antibiotic significantly improved the survival of mice infected with three times the lethal dose (LD(90)) of the highly cytotoxic ExoU-secreting strain, PA103. This synergistic effect was primarily due to enhanced bactericidal effect and protection against lung injury, which prevented bacterial dissemination to other organs. Hence, the combination of Mab166 with antibiotic administration provides a new, more effective strategy against P. aeruginosa airway infection, especially when large numbers of highly virulent strains are present.

Secretion of Pseudomonas aeruginosa type III cytotoxins is dependent on pseudomonas quinolone signal concentration.

Pseudomonas aeruginosa is an opportunistic pathogen that can, like other bacterial species, exist in antimicrobial resistant sessile biofilms and as free-swimming, planktonic cells. Specific virulence factors are typically associated with each lifestyle and several two component response regulators have been shown to reciprocally regulate transition between biofilm-associated chronic, and free-swimming acute infections. Quorum sensing (QS) signal molecules belonging to the las and rhl systems are known to regulate virulence gene expression by P. aeruginosa. However the impact of a recently described family of novel quorum sensing signals produced by the Pseudomonas Quinolone Signal (PQS) biosynthetic pathway, on the transition between these modes of infection is less clear. Using clonal isolates from a patient developing ventilator-associated pneumonia, we demonstrated that clinical observations were mirrored by an in vitro temporal shift in isolate phenotype from a non-secreting, to a Type III cytotoxin secreting (TTSS) phenotype and further, that this phenotypic change was PQS-dependent. While intracellular type III cytotoxin levels were unaffected by PQS concentration, cytotoxin secretion was dependent on this signal molecule. Elevated PQS concentrations were associated with inhibition of cytotoxin secretion coincident with expression of virulence factors such as elastase and pyoverdin. In contrast, low concentrations or the inability to biosynthesize PQS resulted in a reversal of this phenotype. These data suggest that expression of specific P. aeruginosa virulence factors appears to be reciprocally regulated and that an additional level of PQS-dependent post-translational control, specifically governing type III cytotoxin secretion, exists in this species.

Viable bacterial colonization is highly limited in the human intestine in utero.

Mucosal immunity develops in the human fetal intestine by 11-14 weeks of gestation, yet whether viable microbes exist in utero and interact with the intestinal immune system is unknown. Bacteria-like morphology was identified in pockets of human fetal meconium at mid-gestation by scanning electron microscopy (n = 4), and a sparse bacterial signal was detected by 16S rRNA sequencing (n = 40 of 50) compared to environmental controls (n = 87). Eighteen taxa were enriched in fetal meconium, with Micrococcaceae (n = 9) and Lactobacillus (n = 6) the most abundant. Fetal intestines dominated by Micrococcaceae exhibited distinct patterns of T cell composition and epithelial transcription. Fetal Micrococcus luteus, isolated only in the presence of monocytes, grew on placental hormones, remained viable within antigen presenting cells, limited inflammation ex vivo and possessed genomic features linked with survival in the fetus. Thus, viable bacteria are highly limited in the fetal intestine at mid-gestation, although strains with immunomodulatory capacity are detected in subsets of specimens.

Bacteroides are associated with GALT iNKT cell function and reduction of microbial translocation in HIV-1 infection.

Invariant natural killer T (iNKT) cells are innate-like T cells that respond to lipid antigens presented by CD1d. These immunoregulatory cells have the capacity for rapid cytokine release after antigen recognition and are essential for the activation of multiple arms of the immune response. HIV-1 infection is associated with iNKT cell depletion in the peripheral blood; however, their role in the gastrointestinal-associated lymphoid tissue (GALT) is less well studied. Our results show that iNKT cells are found at a higher frequency in GALT compared with blood, particularly in HIV-1 elite controllers. The capacity of iNKT cells to produce interleukin-4 (IL-4) and IL-10 in the GALT was associated with less immune activation and lower markers of microbial translocation, whereas regulatory T cell frequency showed positive associations with immune activation. We hypothesized that the composition of the microbiota would influence iNKT cell frequency and function. We found positive associations between the abundance of several Bacteroides species and iNKT cell frequency and their capacity to produce IL-4 in the GALT but not in the blood. Overall, our results are consistent with the hypothesis that GALT iNKT cells, influenced by certain bacterial species, may have a key role in regulating immune activation in HIV-1 infection.

Lactobacillus johnsonii supplementation attenuates respiratory viral infection via metabolic reprogramming and immune cell modulation.

Regulation of respiratory mucosal immunity by microbial-derived metabolites has been a proposed mechanism that may provide airway protection. Here we examine the effect of oral Lactobacillus johnsonii supplementation on metabolic and immune response dynamics during respiratory syncytial virus (RSV) infection. L. johnsonii supplementation reduced airway T helper type 2 cytokines and dendritic cell (DC) function, increased regulatory T cells, and was associated with a reprogrammed circulating metabolic environment, including docosahexanoic acid (DHA) enrichment. RSV-infected bone marrow-derived DCs (BMDCs) from L. johnsonii-supplemented mice had altered cytokine secretion, reduced expression of co-stimulatory molecules, and modified CD4+ T-cell cytokines. This was replicated upon co-incubation of wild-type BMDCs with either plasma from L. johnsonii-supplemented mice or DHA. Finally, airway transfer of BMDCs from L. johnsonii-supplemented mice or with wild-type derived BMDCs pretreated with plasma from L. johnsonii-supplemented mice reduced airway pathological responses to infection in recipient animals. Thus L. johnsonii supplementation mediates airway mucosal protection via immunomodulatory metabolites and altered immune function.

Maternal group B Streptococcus and the infant gut microbiota.

Early patterns of gut colonization may predispose children to adult disease. Exposures in utero and during delivery are associated with the infant gut microbiome. Although ~35% of women carry group B strep (GBS; Streptococcus agalactiae) during pregnancy, it is unknown if GBS presence influences the infant gut microbiome. As part of a population-based, general risk birth cohort, stool specimens were collected from infant's diapers at research visits conducted at ~1 and 6 months of age. Using the Illumina MiSeq (San Diego, CA) platform, the V4 region of the bacterial 16S rRNA gene was sequenced. Infant gut bacterial community compositional differences by maternal GBS status were evaluated using permutational multivariate analysis of variance. Individual operational taxonomic units (OTUs) were tested using a zero-inflated negative binomial model. Data on maternal GBS and infant gut microbiota from either 1 (n=112) or 6-month-old stool (n=150) specimens was available on 262 maternal-child pairs. Eighty women (30.5%) were GBS+, of who 58 (72.5%) were given intrapartum antibiotics. After adjusting for maternal race, prenatal antifungal use and intrapartum antibiotics, maternal GBS status was statistically significantly associated with gut bacterial composition in the 6 month visit specimen (Canberra R 2=0.008, P=0.008; Unweighted UniFrac R 2=0.010, P=0.011). Individual OTU tests revealed that infants of GBS+ mothers were significantly enriched for specific members of the Clostridiaceae, Ruminococcoceae, and Enterococcaceae in the 6 month specimens compared with infants of GBS- mothers. Whether these taxonomic differences in infant gut microbiota at 6 months lead to differential predisposition for adult disease requires additional study.

Nutritional support in children with end-stage liver disease: a randomized crossover trial of a branched-chain amino acid supplement.

Malnutrition is common in children with end-stage liver disease (ESLD) awaiting orthotopic liver transplantation (OLT), and nutritional support is assuming an important role in preoperative management. To evaluate preoperative nutritional therapy, 19 children (median age 1.25 y) with ESLD awaiting OLT were prospectively studied. Two high-energy, isoenergetic and isonitrogenous nutritional formulations delivered nasogastrically were compared: a branched-chain amino acid (BCAA)-enriched semielemental formulation and a matched standard semielemental formation. Twelve of 19 patients completed a randomized controlled study before OLT and 10 of 19 completed a full crossover study. Improvements in weight and height occurred during the BCAA supplements, with no statistical change on the standard formulation. Significant increases in total body potassium, midupper arm circumference, and subscapular skinfold thickness occurred during the BCAA supplements, whereas no significant changes occurred during the standard formulation period. Significantly fewer albumin infusions were required during the BCAA supplement. These findings suggest that BCAA-enriched formulas have advantages over standard semielemental formulas in improving nutritional status in children with ESLD, and are deserving of wider application and study.

The nature of malnutrition in children with end-stage liver disease awaiting orthotopic liver transplantation.

To evaluate malnutrition in chronic liver disease, and its relationship to nutrient deficiencies and hepatic dysfunction, 27 children with end-stage liver disease were studied. Mean protein-energy intakes were 70% of recommended daily intakes. The patients were underweight and stunted with reduced mean triceps and subscapular skinfold thicknesses and midupper arm circumference. Mean total body potassium was only 63 +/- 18% of that expected for age and sex. Deficiency of essential fatty acids (32%), and low concentrations of fat-soluble vitamins (A, 92%; E, 32%), iron (32%), zinc (42%), and selenium (13%) were common. Serum ammonia concentrations were raised in all patients, and increased methionine, tyrosine, and glutamic acid, and reduced glutamine concentrations were noted. There was no correlation between the degree of malnutrition and the degree of liver synthetic function, the degree of cholestasis, or the degree of liver injury. We suggest that potentially correctable factors in addition to liver failure (eg, inadequate absorbed intake) were important determinants of malnutrition in these patients.

A new technique for early detection of portal vein and arterial thromboses. Indwelling mesenteric venous catheterization and relevance to small bowel transplantation.

The aim of this study was to ascertain whether, in an animal model, continuous monitoring of mesenteric venous pressure (MVP) via an indwelling mesenteric venous catheter could assist in early detection of thrombosis of the portal vein (PVT) and superior mesenteric artery (SMAT). The role of portography via the catheter was also studied in confirming these complications. An animal model of PVT and SMAT was developed in pigs. At laparotomy, a 20-cm jejunal loop was isolated and a heparin-coated catheter was inserted into a mesenteric vein of the isolated jejunum and connected to a pressure transducer. Conditions of PVT were simulated by progressive occlusion of the portal vein (PV) using a silastic tourniquet and those of SMAT by superior mesenteric artery (SMA) clamping. MVPs (mm Hg) were found to significantly increase with all degrees of PV occlusion (P < 0.01, Student's t test) and to significantly decrease after SMA occlusion (P < 0.01). Portography clearly demonstrated all degrees of PV stenosis after PV occlusion and stasis of contrast medium during SMA occlusion. The authors feel that this method enables rapid diagnosis of PVT and SMAT and may be useful in the monitoring of the therapy for these complications after small bowel transplantation.

Use of monoethylglycinexylidide as a liver function test in the liver transplant recipient.

The hepatic conversion of lignocaine to monoethylglycinexylidide (MEGX) has been used as a real time monitor of liver function in liver transplant recipients. Data are reported for the first 4 weeks after transplant in 50 consecutive orthotopic liver grafts in 47 adults. The MEGX concentration was significantly depressed by approximately 50% in those patients in whom there was a complicated clinical course (excluding steroid-sensitive rejection) after transplantation, compared with patients in whom major complications did not occur. The MEGX concentration in the recipients after transplant was independent of the donor MEGX concentration, but, in addition to the patient's clinical status, was strongly influenced by the recipients pretransplant biochemical profile, being inversely related to the pretransplant bilirubin concentration. MEGX concentrations < 25 micrograms/L in the first 36 hr after revascularization were predictive of greater morbidity and mortality.

Clinicopathological analysis of liver allograft biopsies with late centrilobular necrosis: a comparative study in 54 patients.

BACKGROUND: Centrilobular necrosis (CLN) in liver allografts can be a difficult lesion to interpret histologically. Although long recognized in association with developing chronic rejection, recent studies have described the lesion in association with a number of other disease processes. To clarify the histologic features that could allow a specific diagnosis to be made and to determine the outcome in different diagnostic groups, we assessed biopsies from 54 patients with CLN. METHODS: Biopsies were classified as CLN with acute cellular rejection (ACR), CLN with hepatitis, CLN with developing chronic rejection (CR), and CLN of other etiology. Histologic features were assessed and then compared between groups, and clinical outcomes were noted. RESULTS: Discriminating features for the different groups were as follows: CLN and ACR showed bile duct injury, endothelialitis, and acinar congestion. CLN and CR showed severe bile duct injury, bile duct loss, or centrilobular swelling. CLN and hepatitis was often a diagnosis of exclusion, although interface hepatitis was more common in this group. Cases of autoimmune hepatitis usually demonstrated plasma cell predominance in the portal and acinar inflammatory infiltrate. Significantly, there was considerable overlap in the histologic features between the groups, accounting for the diagnostic difficulty. Patients in whom the CLN was associated with CR or vascular complications generally required retransplantation or died, but in the groups with ACR and hepatitis, the outcome was more favorable. CONCLUSIONS: With regard to most liver allograft biopsies showing late CLN, it is possible to make a specific diagnosis despite overlapping histologic features; this allows specific therapy to be instituted. Ultimately this is likely to contribute to improved graft survival.

A randomized trial of OKT3-based versus cyclosporine-based immunoprophylaxis after liver transplantation. Long-term results of a European and Australian multicenter study.

A multicenter randomized trial was performed to compare two immunosuppressive protocols after first ABO-compatible liver transplantation. Forty six patients were randomized to a 14-day treatment with Orthoclone (OKT3) in association with steroids and azathioprine, cyclosporine being progressively introduced on day 11 posttransplant. Fifty patients were randomized to a standard protocol of cyclosporine with steroids and azathioprine. Minimum follow-up was 1 year and graft and patient survivals were updated for the purpose of the study. The cumulative 1-year incidence of acute rejection tended to be greater in the cyclosporine group (75%) than in the OKT3 group (67%), especially when patients who did not receive full-course treatment with OKT3 were excluded (59%). Renal function was better preserved during the first two postoperative weeks in the OKT3 group than in the control group but plasma creatinine levels were comparable in both groups thereafter. The incidence of severe infections was lower in the OKT3 group (13.6%) than in the cyclosporine group (32%). The 4-year incidences of patient and graft survival in the OKT3 group (69% and 61%, respectively) were not different from those in the cyclosporine group (62% versus 54%, respectively). Thus this prospective trial shows that OKT3 immunoprophylaxis is a safe alternative to cyclosporine immunoprophylaxis in unselected recipients of a first liver graft.

Population pharmacokinetics of tacrolimus in children who receive cut-down or full liver transplants.

BACKGROUND: The aim of this study was to investigate the population pharmacokinetics of tacrolimus in pediatric liver transplant recipients and to identify factors that may explain pharmacokinetic variability. METHODS: Data were collected retrospectively from 35 children who received oral immunosuppressant therapy with tacrolimus. Maximum likelihood estimates were sought for the typical values of apparent clearance (CL/F) and apparent volume of distribution (V/F) with the program NONMEM. Factors screened for influence on the pharmacokinetic parameters were weight, age, gender, postoperative day, days since commencing tacrolimus therapy, transplant type (whole child liver or cut-down adult liver), liver function tests (bilirubin, alkaline phosphatase [ALP], aspartate aminotransferase [AST], gamma-glutamyl transferase [GGT], alanine aminotransferase [ALT]), creatinine clearance, hematocrit, corticosteroid dose, and concurrent therapy with metabolic inducers and inhibitors of tacrolimus. RESULTS: No clear correlation existed between tacrolimus dosage and blood concentrations (r2=0.003). Transplant type, age, and liver function test values were the most important factors (P<0.01) that influenced the pharmacokinetics of tacrolimus. CL/F estimates were greater in whole liver recipients, decreased with increasing patient age and AST values, and increased with increasing GGT values. Average parameter estimates were CL/F=5.75 L/h (cut-down liver), CL/F=44 L/h (whole liver), and V/F=617 L. Marked intersubject variability (CV%=110% to 297%) and residual variability (CV%=42%) was observed. CONCLUSIONS: Pharmacokinetic information obtained in this study may assist physicians in making individualized dosage decisions in regard to tacrolimus in pediatric liver transplant recipients. Children who received a whole child's liver appeared to retain "pediatric" clearance, whereas those who received a cut-down adult liver had "adult" clearances (on average 7-fold less).

Role of donor leukocyte chimerism in establishing the etiology of neutropenia after liver transplantation.

BACKGROUND: The quantitation of donor leukocyte chimerism may aid in establishing the etiology of neutropenia after liver transplantation. METHODS: The incidence and clinical and laboratory characteristics of severe neutropenia were studied in adults who have undergone liver transplantation at our institution over the last 4 years. RESULTS: Severe neutropenia developed in 5 of 156 patients (3%). The clinical and pathological features were nonspecific. In two patients with a delayed diagnosis of graft-versus-host disease (GVHD), donor leukocytes comprised > or = 50% of the circulating peripheral blood mononuclear cells. In a third patient, an earlier diagnosis of GVHD was suspected on the basis of a donor leukocyte count of 3-10% in the peripheral blood. In contrast, donor leukocyte chimerism was < or = 0.01% in two patients with probable drug-induced neutropenia CONCLUSIONS: The determination of donor leukocyte chimerism has an important role in the investigation of neutropenia after liver transplantation, allowing early diagnosis and treatment of GVHD.

Anatomic resection for severe liver trauma.

BACKGROUND: Most publications during the past decade have condemned the use of anatomic resection for liver trauma and advocated a conservative surgical approach when operative intervention was required. This policy has been supported by the high mortality rate reported by most authorities. The purpose of this study was to assess the results of anatomic hepatic resection for liver trauma in an institution in which the hepatobiliary surgeons are responsible for the management of severe liver injuries. METHODS: During the period 1983 to 1996, 287 patients with liver injuries were admitted to the hospital and 37 patients with severe liver trauma underwent anatomic resection. Demographic, clinical, operative, and postoperative data were collected and analyzed. The resections performed included right hemihepatectomy (n = 27), left hemihepatectomy (n = 1), left lateral segment resection (n = 5), and segmental resection (n = 4). RESULTS: There were three postoperative deaths after right hemihepatectomy (11.1%) and an overall mortality rate of 8.1%. There were no intraoperative deaths. Postoperative complications occurred in 22 patients (60%) and were most frequent in patients with concomitant injuries to other systems. Liver-related morbidity occurred in seven patients (19%). The median postoperative stay was 20 days. CONCLUSIONS: Anatomic hepatic resection for trauma is associated with low mortality and liver-related morbidity rates when performed by experienced hepatobiliary surgeons, and its role in the management of severe hepatic trauma should be reevaluated.